MainActivity_step2.java

public class MainActivity extends AppCompatActivity implements BooksView {

    EditText editText;
    ImageButton imageButton;
    BooksAdapter adapter;
    ListView listView;
    TextView textNoDataFound;
    private BooksPresenter presenter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        editText = (EditText) findViewById(R.id.editText);
        imageButton = (ImageButton) findViewById(R.id.imageButton);
        textNoDataFound = (TextView) findViewById(R.id.text_no_data_found);

        adapter = new BooksAdapter(this, -1);

        listView = (ListView) findViewById(R.id.listView);
        listView.setAdapter(adapter);

        imageButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                presenter.performSearch(getUserInput());
            }
        });
        
        // Note: Don't do this on production code, use Dependency Injection instead
        // to provide the BooksInteractor and the BooksPresenter to the View
        // Learn how to use Dagger 2 here: 
        // https://medium.com/@Miqubel/understanding-dagger-2-367ff1bd184f#.s2jza32df
        BooksInteractor interactor = new BooksInteractorImpl();
        presenter = new BooksPresenter(interactor);
        presenter.bind(this);
    }
        
    @Override
    protected void onDestroy() {
        presenter.unbind();
        super.onDestroy();
    }

    @Override
    public void updateUi(List<Book> books) {
        if (books.isEmpty()) {
            // if no books found, show a message
            textNoDataFound.setVisibility(View.VISIBLE);
        } else {
            textNoDataFound.setVisibility(View.GONE);
        }
        adapter.clear();
        adapter.addAll(books);
    }

    private String getUserInput() {
        return editText.getText().toString();
    }
}